1. Field of the Invention
The invention is directed generally to diaphragm pumps and, more particularly, to a diaphragm pump including a signal generator inserted into a diaphragm therein for measuring displacement of the diaphragm.
2. Discussion of the Related Art
Diaphragm pumps are known. Such pumps generally include a first chamber for liquid or fluid to be pumped, a second chamber for drive fluid, a diaphragm separating the first and second chambers and a drive piston driven in oscillating fashion within the second chamber to place the drive fluid alternatively under pressure and under relaxation. The diaphragm is generally displaced in response to the varying pressure placed upon the drive fluid to thereby effect the necessary pumping action.
The liquid to be pumped is supplied to the first chamber through an intake valve and is removed therefrom via a discharge valve located within a pressure line coupled thereto. A supply chamber for the drive fluid is connected to the second chamber via a return line having a pressure relief valve for letting drive fluid off into the supply chamber given excessive back pressure exerted upon the drive fluid by the pumped fluid. The supply chamber is also connected to the second chamber via a refilling line having a refilling valve for replenishing drive fluid in the second chamber given a removal of drive fluid therefrom.
Diaphragm pumps have generally proven to work well in practice. However, a displaced volume of such pumps is subject to fluctuations. First, air bubbles become entrapped in the drive fluid causing the fluid to become relatively elastic. Second, the displacement of the diaphragm into the first chamber is dependent upon, among other things, the resistance in the pressure line as well as the opening pressure of the pressure relief valve in the drive fluid return line. Therefore, because the pumping action is dependent upon the displaced volume, a constant stream of pumped fluid and, consequently, a high constancy of adjustment to the pump to achieve a steady stream is frequently not establishable. In addition, reproducibility of the stream of pumped fluid that is required cannot be realized.